textproduct: Rapid City

KEY MESSAGES

- Severe thunderstorms are expected this afternoon and evening with primary risks of large hail and damaging winds, although a tornado cannot be ruled out.

- Friday will be warm and drier. Showers and thunderstorms will end over south central South Dakota in the morning, but a few thunderstorms will be possible over the Black Hills in the afternoon.

- Hot and dry Saturday.

DISCUSSION

(This Evening Through Thursday) Issued at 122 PM MDT Thu Jun 4 2026

Upper level analysis has mostly zonal flow over the Northern Plains with a shortwave trof moving through the Rockies in Montana and Wyoming. A surface low is currently over the Bighorns with a trough extending northward into central Montana and a stationary boundary stretching across the South Dakota/Nebraska border into northeastern South Dakota. Satellite imagery is showing building cumulus clouds over northeastern Wyoming and southeastern Montana. Temperatures at 18Z were mostly in the 70s with 60s in the Black Hills.

For this afternoon and evening, convective initiation will likely begin over northeastern Wyoming and southeastern Montana as the Black Hills and South Dakota Plains remain fairly well capped. Deep layer shear around 50kts will support the potential for supercell development, with the potential for large hail. The surface boundary near the state line will drift northward later this afternoon. Moisture convergence along the boundary interacting with large-scale ascent from the approaching shortwave, will combine with deep-layer shear of 35-45kt, supporting potential storms with a more outflow dominant storm mode.

Convection will move eastward overnight. lingering into Friday morning. Temperatures will warm Friday, with highs in 80s, some 70s in the Black Hills. Shortwave ridging builds to the west, but diurnally driven showers over the Black Hills can't be ruled out during the afternoon. The shortwave ridge will move over the forecast area on Saturday, resulting in hot and dry conditions. Storm chances return Sunday as the upper level trof deepens over the western US and places our CWA under unsettled southwest flow.

AVIATION

(For the 00Z TAFS Through 00Z Friday Evening) Issued At 517 PM MDT Thu Jun 4 2026

Isolated to scattered, potentially severe, thunderstorms will continue to move over the Black Hills, western South Dakota plains, and northeastern Wyoming this eveing and into the overnight hours. Large hail, frequent lightning, and gusty/erratic winds can be expected with any stronger convective cores. Transient MVFR/IFR conditions also expected around any heavier precipitation cores. Conditions will improve between 10-12z as storms/showers move out of the region.

UNR WATCHES/WARNINGS/ADVISORIES

SD...None. WY...None.